Pipe and condensate boundary film collection and drainage device for installation in said pipe

ABSTRACT

A pipe for passing or discharging wet gases and a condensate edge film reception and discharge device for the installation in such a pipe are described. The pipe is especially designed as wet chimney. The condensate edge film reception and discharge device is arranged at the opening of the pipe or in the interior of the pipe. It includes a droplet separator which is preferably designed as annular separator. By this, an effective removal of the generated condensate edge film is obtained.

The present invention is directed to a pipe for passing or discharging wet gases, especially for passing or discharging flue gases submitted to a scrubbing process, comprising a condensate edge film reception and discharge device having a separation member arranged in the range of the inner edge of the pipe for the separation of a part-gas stream from the gas stream flowing through the pipe and an associated condensate discharge device.

Furthermore, the present invention relates to a condensate edge film reception and discharge device for the installation in a pipe for passing or discharging wet gases.

When wet gases are passed or discharged through pipes condensate is generated by the contact of the gas stream with the relatively cold pipe wall which is developed in the form of a condensate edge film on the inner wall of the pipe. This condensate edge film is passed or entrained by the movement of the gas stream to the opening of the pipe and is discharged from the pipe together with the gas stream and exhausted (into the atmosphere) in the form of liquid droplets, mist etc. Of course, this is not desired and corresponding counter measures have been already taken.

Up to now one has frequently used reheating means in the form of heat exchangers or through direct introduction of energy by means of gas burners behind scrubbers, for instance scrubbers of flue gases, in order to feed the wet gas through large chimneys up to 400 m high without generating excessively much condensate. In this manner especially the ejection of coarse droplets from the chimney which fall down in the direct vicinity of the chimney should be prevented. However, these installations are very expensive and maintenance-intensive or require a high energy expenditure.

Therefore, modern installations were provided with so-called wet chimneys which are about 250 m high. Here, the gas transport is realized by means of pressure raising blowers in front of or behind the scrubber. However, also in this case the result is a high amount of condensate within the chimney and thus the ejection of coarse droplets from the chimney which fall down in the direct vicinity of the chimney due to the cooling of the wet gases on their way to the outlet of the chimney. Up to now only in a few cases installations, as for instance axial cyclones, were installed in the large chimneys apart from simple drainage means since these installations result in very high energy losses due to the high velocities in the chimney and also do not represent up to now a satisfying solution with respect to the discharge of droplets.

Furthermore, for reducing the ejection of droplets one has installed in many wet chimneys so-called film traps or other baffles which shall prevent the entraining of liquid films along the chimney wall. However, these measures are normally useful only in a limited manner since the liquid film is entrained or droplets are extricated from the film due to the high gas velocities in such chimneys. Accordingly, even with these installations a detrimental ejection of droplets cannot be completely prevented.

Another counter measure consists in providing such wet chimneys with condensate edge film reception and discharge devices. These devices are arranged at the openings of the wet chimneys and cause a separation of a part-gas stream from the gas stream flowing through the wet chimney wherein this part-gas stream is to entrain the formed condensate edge film and thus is to separate the same from the main gas stream in the central range of the chimney. The condensate separating then from the part-gas stream is caught and discharged through a condensate discharge device. However, these known condensate edge film reception and discharge devices or “edge film traps” are connected with problems since the amount of the liquid which is introduced into the edge film reception and discharge device depends considerably from the leading of the gas stream to the device and into the device. Since the path passed by the part-gas stream in the condensate edge film reception and discharge device has only a small width compared with the pipe diameter a gas jamming zone can be formed in this region whereby the minimum velocity necessary for the condensate discharge is fallen short so that the condensate edge film is at least not completely entrained by the part-gas stream but is conveyed outwardly at least partly past the edge film trap with the central gas stream out of the wet chimney so that the provided edge film trap becomes effective only partly or not at all. This “jamming effect” is still enforced by small outlet openings of the gas stream from the edge film trap or by several deflections of the gas stream in the same. Accordingly, a not unimportant part of the edge film is entrained by the central gas stream and is discharged into the atmosphere in the form of droplets, mist etc. in spite of the arrangement of such condensate edge film reception and discharge devices or edge film traps.

It is the object of the present invention to provide a pipe for passing or discharging wet gases which has an especially effective condensate edge film reception and discharge device.

According to the invention this object is attained with a pipe of the above-cited kind by the feature that the condensate edge film reception and discharge device in its path passed by the separated part-gas stream has a droplet separator passed by the part-gas stream.

The above-described disadvantages of the prior art are avoided with the inventive solution. Due to the arrangement of a droplet separator no narrowing or deflection of the flow channel arranged in the condensate edge film reception and discharge device has to be realized in order to carry away the condensate. The droplet separator provided according to the invention is rather arranged behind the annular space formed by the separation member and extends preferably over the complete annular space so that preferably the whole cross-section of the annular space is covered by the droplet separator and is flown through by the part-gas stream. Accordingly, a relatively wide flow path exists with respect to the part-gas stream so that the minimum flow velocity required for an effective droplet separation can be maintained. Substantially no significant jamming effect prior to the entrance into the condensate edge film reception and discharge device takes place so that the edge film is detached in an effective manner and can be entrained by the part-gas stream without the effect that a part of the edge film enters the main gas stream.

Preferably, the part-gas stream is guided out of the pipe without deflection and passes the droplet separator arranged according to the invention. Accordingly, in this embodiment the part-gas stream is guided substantially parallel with respect to the main gas stream. However, the invention provides also an embodiment according to which the part-gas stream is deflected, especially for about 90°, so that it leaves the pipe perpendicularly with respect to the pipe axis.

In any case the droplet separator provided according to the invention separates the entrained liquid of the condensate edge film from the discharged part-gas stream and leads the liquid to the associated condensate discharge device which, for instance, can be formed as gas-stream free annular channel which can be drained by means of drainage lines.

According to a special embodiment of the invention the condensate edge film reception and discharge device is arranged at the pipe opening. Generally, the pipe can be arranged vertically or horizontally or can have any inclined position. Preferably, the pipe is designed as so-called wet chimney wherein the condensate edge film reception and discharge device is arranged at the opening of the wet chimney in the above-described embodiment. Here, the separation member extends preferably beyond the end of the pipe or of the chimney and forms, together with a radially outer limiting member outside of the pipe wall or chimney wall, an annular space which is flown through by the part-gas stream and at the outlet end of which the droplet separator is disposed.

According to another embodiment of the invention the condensate edge film reception and discharge device is arranged in the interior of the pipe. Also in this case a separation member disposed in the interior of the pipe and which is preferably annularly formed causes the separation of a part-gas stream in the region of the pipe wall which flows through the annular space limited by the separation member and the pipe wall. A droplet separator is arranged behind this annular space wherein also in this case the separated liquid is preferably led into a gas stream-free annular channel which can be drained by means of drainage lines. Accordingly, in this embodiment the condensate edge film reception and discharge device is completely situated in the interior of the pipe while in the above-described embodiment (arrangement at the pipe opening) it is disposed partly in the interior of the pipe and partly outside of the pipe.

Preferably, the droplet separator is so arranged in the condensate edge film reception and discharge device that it is vertically passed from the separated gas stream (part-gas stream). This embodiment is especially used when the pipe is arranged vertically which is the case with wet chimneys. Accordingly, in this case the part-gas stream is not deflected and is led substantially parallel with respect to the main gas stream.

However, the invention provides also a droplet separator which is passed horizontally and which is especially used in connection with lying pipes, however, also with vertically arranged pipes wherein here the part-gas stream is deflected for about 90°.

Preferably, the droplet separator is formed as annular separator and, as mentioned above, is arranged behind the annular space flown through by the part-gas stream within the condensate edge film reception and discharge device.

Especially, the condensate reception and discharge device includes an annular space formed between the separation member and the pipe wall which expands in gas flow direction to a larger annular space at the end of which the droplet separator (annular separator) is arranged.

As mentioned, the annular separator is installed in such a manner that it is flown through either vertically or horizontally.

When the condensate edge film reception and discharge device is arranged in the interior of the pipe the annular separator is disposed between the pipe wall and the separation member. When the condensate edge film reception and discharge device is arranged at the pipe opening the annular separator is disposed between the separation member and a gas flow path limiting member.

Preferably, the annular separator includes a plurality of radially arranged droplet separator lamellas extending between a radially inner and radially outer or upper and lower limiting wall. Accordingly, when the annular separator is installed such that it is vertically flown through a radially inner and a radially outer limiting wall in annular shape are present wherein the individual droplet separator lamellas are preferably not arranged parallel but radially extending. Accordingly, in this case the distance between the individual lamellas is larger radially outside than radially inside. The droplet separator lamellas can be designed in known manner, i.e. in a wave-like manner, and can be provided with intercepting pockets. Such embodiments are known to the expert in the art so it is no more necessary to describe the same in detail here.

When the annular separator is installed such that it is horizontally flown through an upper and a lower limiting wall are present between which radially extending droplet separator lamellas are disposed. Also in this case the lamellas have preferably a smaller distance from one another radially inside than radially outside.

Preferably, furthermore the condensate edge film reception and discharge device includes a condensate reception trough with drain which is appropriately designed as annular space, too, and which is situated outside of the gas flow path flown through by the part-gas stream. The liquid is discharged through the drain or through a suitable drainage. It is essential that the condensate reception trough or the corresponding annular space is substantially free of flow so that the separated liquid can no more be entrained again by the gas stream.

With another embodiment of the invention the separation member is designed conically and narrows in gas flow direction. This embodiment is especially used when the condensate edge film reception and discharge device is arranged within the pipe in order to obtain in this manner no abrupt but a gradual narrowing of the flow path of the main gas stream at the place of the arrangement of the condensate edge film reception and discharge device.

Of course, when a condensate edge film reception and discharge device is arranged within the pipe several devices can be disposed one behind the other so that a multi-stage edge film reception and discharge device results.

Furthermore, the present invention is directed to a condensate edge film reception and discharge device for the installation in a pipe of the above-cited kind. Such a condensate edge film reception and discharge device can include all the above-cited features. Accordingly, it is not necessary to repeat these features in detail here.

In the following the invention is described by means of examples in connection with the drawings in detail. Of the drawings

FIG. 1 shows a schematic sectional representation of the opening of a wet chimney with a first embodiment of a condensate edge film reception and discharge device;

FIG. 2 shows a schematic sectional representation according to FIG. 1 with a second embodiment of a condensate edge film reception and discharge device;

FIG. 3 shows a schematic sectional representation of a part of a wet chimney with another embodiment of a condensate edge film reception and discharge device;

FIG. 4 shows a schematic top view on a part of a droplet separator of the condensate edge film reception and discharge device formed as annular separator; and

FIG. 5 shows an enlarged representation of a part of the annular separator of FIG. 4.

In the schematic vertical cross-sectional representation of FIG. 1 the end wall at the opening of a wet chimney is provided with reference number 9. A condensate edge film reception and discharge device 1 is schematically shown at the opening of the wet chimney. The device includes a separation member 2 which is annularly formed and extends from outside into the interior of the chimney. In this manner an annular space 7 is formed between the separation member 2 and the chimney wall 9 wherein this annular space 7 expands to a larger annular space 8 which is formed between an annular limiting wall 3 and the separation member 2. The gas flow direction extends from below to above in FIG. 1. A droplet separator in the shape of an annular separator 4 is arranged in gas flow direction behind the annular space 8 and is also situated between the separation member 1 and the limiting wall 3. An annular condensate reception space 5 having a condensate drain 6 is arranged below the annular space 8 at the outside of the chimney wall 9.

The condensate edge film reception and discharge device 1 functions in the following manner:

The wet gas flowing in the wet chimney upwardly to the opening comes to the separation member 2 and is divided by the same into a central part-gas stream and a radially outer part-gas stream which enters the annular space 7. The condensate generated at the inner side of the chimney wall 9 and upwardly entrained by the gas stream is entrained by the formed radially outer part-gas stream into the annular space 7 and enters the wider annular space 8 and from there the droplet separator 4 arranged therebehind. This droplet separator formed as annular separator has a plurality of radially arranged wave-like lamellas with interception pockets. When passing the annular separator the condensate entrained with the part-gas stream is separated and gets downwardly into the annular condensate reception space 5 by gravity and is discharged through the drain 6 out of the same. The part-gas stream having passed the droplet separator 4 is discharged to the atmosphere.

In the droplet separator 4 shown in FIG. 1 the individual droplet separator lamellas are arranged radially and vertically. The droplet separator is flown through in vertical direction. FIG. 2 shows an embodiment according to which the droplet separator 4 is flown through horizontally. Also the condensate edge film reception and discharge device shown in FIG. 2 has a separation member 2, an annular space 7 formed between the chimney wall 9 and the separation member 2, a subsequent enlarged annular space 8, an annular condensate reception space 5 and a condensate drain 6. The part-gas stream entraining the condensate edge film is deflected for about 90° into the annular space 8 from the annular space 7 and flows from there horizontally into the droplet separator 4. The same is also designed as annular separator and has radially and vertically arranged droplet separator lamellas extending between an upper and a lower limiting wall. They are horizontally flown through as shown by the arrow. The condensate separated in the droplet separator is intercepted in the annular space 5 and is discharged through the drain 6. The part-gas stream moves into the atmosphere from the droplet separator 4.

FIG. 3 shows a schematic vertical sectional view of a wet chimney wherein in this embodiment a condensate edge film reception and discharge device 10 is arranged in the interior of the wet chimney and not at the opening thereof. Also in this embodiment the condensate edge film reception and discharge device 10 includes an annular separation member 11 which conically narrows in gas flow direction in FIG. 3 from below to above. The separation member 11 is upwardly deflected in its lower part and includes a portion extending parallel with respect to the chimney wall 19 and limiting with the chimney wall an annular space 12. The annular space 12 expands upwardly to form a wider annular space 13 behind which a droplet separator 14 formed as annular separator is disposed. In the interior of the chimney several droplet separator edge film reception and discharge devices shown in FIG. 3 can be arranged one behind the other in gas flow direction.

A part-gas stream is separated from the gas stream by the separation member 11 and enters the annular space 12 wherein it entrains the condensate edge film formed at the inner side of the chimney wall 19. Then the part-gas stream moves into the enlarged annular space 13 and from there into the droplet separator 14. The droplet separator is designed as annular separator and has a plurality of radially and vertically arranged wave-like droplet separator lamellas provided with interception pockets. The part-gas stream passes the droplet separator 14 wherein the entrained condensate is separated and intercepted in an annular condensate reception space 15 formed between the lower part of the separation member 11 and its portion extending parallel with respect to the chimney wall. From there the condensate is discharged by means of a drainage shown schematically at 16. The part-gas stream having passed the droplet separator 14 then unites again with the main gas stream of the wet chimney.

FIG. 4 shows a schematic top view of a part of the droplet separator 4 formed as annular separator. The annular separator has a plurality of radially arranged wave-like droplet separator lamellas 21 which are provided with interception noses. Such lamellas are known so that their construction has not to be described in detail here. The distance between the lamellas 22 is larger radially outside than radially inside. The lamellas extend between an outer wall 21 and an inner wall 20 which are formed by the separation member 2 and the outer limiting wall 3 in the embodiment of FIG. 1, by the separation member 2 deflected around 90° and a lower limiting wall in the embodiment of FIG. 2 and by a portion of the separation member 11 parallel to the chimney wall and an outer limiting wall disposed at the chimney wall in the embodiment of FIG. 3.

FIG. 5 shows a larger representation of the droplet separator portion of FIG. 4. One recognizes the individual wave-like lamellas 22 with corresponding interception noses 23. The shown annular separator is flown through vertically. 

1. A pipe for passing or discharging wet gases, especially for passing or discharging flue gases submitted to a scrubbing process, comprising a condensate edge film reception and discharge device including a separation member for separating a part-gas stream from the gas stream passing the pipe which is arranged in the range of the inner edge of the pipe, and an associated condensate discharge device, characterized in that the condensate edge film reception and discharge device (1, 10), in its path passed by the separated part-gas stream, includes a droplet separator (4, 14) passed by the part-gas stream.
 2. The pipe according to claim 1, characterized in that the condensate edge film reception and discharge device (1) is arranged at the orifice of the pipe.
 3. The pipe according to claim 1, characterized in that the condensate edge film reception and discharge device (10) is arranged in the interior of the pipe.
 4. The pipe according to one of the preceding claims, characterized in that the droplet separator (4, 14) is formed as annular separator.
 5. The pipe according to one of the preceding claims, characterized in that the droplet separator (4, 14) is arranged in the condensate edge film reception and discharge device (1, 10) in such a manner that it is vertically flown through by the separated gas stream.
 6. The pipe according to one of the claims 1-4, characterized in that the droplet separator (4) is arranged in the condensate edge film reception and discharge device (1) in such a manner that it is horizontally flown through by the separated gas stream.
 7. The pipe according to one of the claims 4-6, characterized in that the annular separator is disposed between the chimney wall (19) and the separation member (11) when the condensate edge film reception and discharge device (10) is arranged in the interior of the pipe or between the separation member (2) and a gas path limiting member (3) when the condensate edge film reception and discharge device (1) is arranged at the opening of the pipe.
 8. The pipe according to one of the preceding claims, characterized in that the separation member (11) is formed conically and narrows in gas flow direction.
 9. The pipe according to one of the claims 4-8, characterized in that the annular separator has a plurality of radially arranged droplet separator lamellas (22) extending between a radially inner and radially outer or upper and lower limiting wall (20, 21).
 10. The pipe according to one of the preceding claims, characterized in that the condensate discharge device includes a condensate reception trough (5, 15) with drain (6, 16).
 11. The pipe according to one of the preceding claims, characterized in that it is designed as wet chimney.
 12. The pipe according to one of the preceding claims, characterized in that the condensate edge film reception and discharge device (1, 10) includes an annular space (7, 12) formed between the separation member (2, 11) and the chimney wall (2, 19) and expanding in gas flow direction to a larger annular space (8, 13) at the end of which the droplet separator (4, 14) is disposed.
 13. A condensate edge film reception and discharge device for the installation in a pipe according to one of the preceding claims. 